[TASK] FollowUp to add support for having files outside the t3d/xml

Fix functional tests.

Resolves: #57379
Change-Id: Iafbf4e2b7e68dd27b488f20141f34680f57bc9c4
Reviewed-on: https://review.typo3.org/30955
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters